Cytokine analysis of BAL samples showed significantly higher levels of IL-1β in Fibulin-4R/R but not in Fibulin-4+/R as compared to Fibulin-4+/+ mice (Figure 4D) Interestingly, IL-1β is a pro-inflammatory cytokine which is mainly produced by activated macrophages and which is increased in patients with COPD [19], [20]. This evidence concerns the gene IL1B and chronic obstructive pulmonary disease.